Implement local climb discovery/explore features

[marcodejongh]

Overview

Aurora's explore endpoint requires apptoken. Build local discovery using synced climb data.

Scope

• Popular climbs by ascent count from {board}_climb_stats
• Trending climbs (recent ascents)
• Recently added climbs (by created_at)
• Filter by difficulty, quality rating
• Create explore page UI

Technical Details

All data is available locally via shared sync:

• {board}_climb_stats table has ascent counts
• {board}_climbs table has climb metadata
• {board}_ascents table for trending analysis

Related

• Part of Aurora API cleanup (all endpoints now require apptoken except sync)